[CLI][subpath aliasing] allow for custom alias setup

[andrewrubin]

Add a piece of config for the CLI, that sets a base subpath alias for the src directory in your project.

Thinking we should default this to @local since that's what the corgi setup uses.

[marlonmarcello]

Moving comment from #33 here

For this to work we'll need:

1. To ask users what aliases they are using for components, utilities and any other type if item we have
2. When copying files we need to transform the imports
   2.1. This will probably require dealing with raw content, could have shitty performance and potentially slow down the process as we'll need to do much more I/O

If it turnout out that doing this slows down the process too much it might be better to just keep the instructions for the user to manually update the imports as that is really low effort.